import math

x1, y1, x2, y2 = [ float( i ) for i in raw_input( ).split( " " ) ]
print( math.sqrt( ( x1 - x2 )**2 + ( y1 - y2 )**2 ) ) import math math float( i ) for i in raw_input( ).split( " " ) for i in raw_input( ).split( " " ) i raw_input( ).split( " " ) ( ).split ( ) raw_input split " " for i in raw_input( ).split( " " ) float( i ) float i x1, y1, x2, y2 = [ float( i ) for i in raw_input( ).split( " " ) ] x1 [ float( i ) for i in raw_input( ).split( " " ) ] y1 x2 y2 print( math.sqrt( ( x1 - x2 )**2 + ( y1 - y2 )**2 ) ) print math.sqrt( ( x1 - x2 )**2 + ( y1 - y2 )**2 ) math.sqrt math sqrt ( x1 - x2 )**2 + ( y1 - y2 )**2 ( x1 - x2 )**2 x1 - x2 x1 x2 2 ( y1 - y2 )**2 y1 - y2 y1 y2 2 y2 = [ float( i ) for i in raw_input( ).split( " " ) ] [ float( i ) for i in raw_input( ).split( " " ) ] y2 x2, y2 = [ float( i ) for i in raw_input( ).split( " " ) ] [ float( i ) for i in raw_input( ).split( " " ) ] x2 x1, y1, x2, y2 = [ float( i ) for i in raw_input( ).split( " " ) ] [ float( i ) for i in raw_input( ).split( " " ) ] x1 y1, x2, y2 = [ float( i ) for i in raw_input( ).split( " " ) ] [ float( i ) for i in raw_input( ).split( " " ) ] y1
import math

x1, y1, x2, y2 = [ float( i ) for i in raw_input( ).split( " " ) ]
print( math.sqrt( ( x1 - x2 )**2 + ( y1 - y2 )**2 ) )